Dumbell scraper

ABSTRACT

A dumbell-shaped paraffin scraper of a type that may be pumped through a paraffin coated portion of a well flow line in order to remove the paraffin.

O Unlted States Patent 1151 3,667,544 Allimon [4 1 June 6, 1972 [54] DUMBELL R 604,058 5/1898 Lukens et al. 15/ 104. 17 1,278,823 9/1918 Ayrhart ...15/104.17 [72] Inventor: Willard F. Allimon, Hacienda Heights, 1,371,792 3/1921 Kirk 15/ 104.17 Calif. 1,756,378 4/1930 Oberhuber... .....l66/153 X 2,810,143 /1957 Reynolds ..166/170 X [73] Assgnee Cmnpflny, New 3,091,294 5/1963 Evans et al ..166/153 x [22] Filed: Sept. 9, 1970 Primary Examiner-David H. Brown PP 70,743 Att0rney-Haro1d L. Denkler and Theodore E. Bieber [52] U.S.CI ..l66/l70, 166/155, /104.17 [57] ABSTRACT [51] Int. Cl ..E2lb 37/02 A dumbell-shaped paraffin scraper of a type that may be [58] Field of Search ..175/170, 153, 15/ 104. 17 P p r g a p ff coated p ni n f a ell fl w line in order to remove the paraffin [56] Reierences Cited 6 Claims, 6 Drawing Figures UNITED STATES PATENTS 3,052,302 9/1962 Lagucki ..166/ X PATENTEDJUH 6 m2 SHEET 10F 2 FIG.

INVENTOR:

FIG.

W. F. ALLMON HIS ATTORNEY FATENTEDJUN 6 me INVENTOR:

' F. ALLMON HIS ATTORNEY DUMBELL SCRAPER BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates to a well tool adapted to be pumped through a flow line and down the tubing of an oil well to remove paraffin from the inner surface of the flow line and tubing.

2. Description of the Prior Art Paraffin accumulation in tubular goods is a costly problem that has long been associated with crude oil production both on land and off shore. On land, easy access to wells can be gained for wire line scraping, hot oil treatment, chemical injection, and other means of paraffin control. In some fields where paraffin is a severe problem, wire line scraping is done at periodic intervals, sometimes once or twice a month.

However, the placement of well head assemblies on the ocean floor, as may be done in developing off shore oil production in areas where it is not feasible to erect stationary platforms which extend above the water surface, raises a new set of problems with regard to carrying out work-over operations such as the cleaning of the paraffin from a tubing string. To clean the tubing with the type of equipment commonly used on land might call for the use of a barge positioned on the surface of the water above the well together with equipment for going down and entering the well head assembly and the tubing string connected thereto. To save the expense of providing such equipment, it has been necessary to develop an entirely new line of well tools which can be pumped through a production tubing string from some remote location, often a mile or more from the well. Such a tool must be capable of passing through one or more curved sections of pipe outside the well and then down the tubing string of the well to perform the desired operation.

A number of paraffin scrapers have been designed and marketed which perform satisfactorily in underwater wells equipped with flow lines having only relatively long radius bends on the order of 5 feet. However, many of these tools are unable to negotiate the relatively short radius bends on the order of 2 to 6 inches which are common in some well head apparatus used for multi-well completions. Polyurathane balls have been used to scrape flow lines in which it is necessary for the scraping tool to pass through such short radius bends. However, such balls tend to wear rapidly and may easily be deformed by hitting stop means of the type often positioned near the bottom of a tubing string to provide a stop for through the flowline tools which are pumped into the well.

SUMMARY OF THE INVENTION The present invention provides a dumbell-shaped tool for scraping parafiin from the interior walls of well flow lines and tubing strings which is capable of going around relatively sharp bends in typical oil field production flow manifolds. The tool, which may be made of wear resistant metal, is capable of forming a sealed surface as it passes through a tee or tubing collar and may be installed with an internal fishing neck for retrieving the tool by wire line should it get stuck within a well tubing.

In its most basic embodiment the tool comprises two sphere shaped scraper elements, preferably formed from a wear resistant material such as steel, having a diameter slightly less than the internal diameter of the pipeline to be scraped and operatively connected to one another by a connector member having a cross sectional thickness substantially less than the internal diameter of the pipeline to be scraped. The scraper is provided with a through-bore means or conduit running longitudinally through the tool so that fluid may bypass the tool as it is run into a well. A check valve means is operatively associated with this through-bore means so that fluid flow through the tool is uni-directional. Thus, in normal operation the through-bore means will be closed as the tool is pumped out of the well which is being treated.

According to a preferred embodiment of this invention the dumbell-shaped scraper is provided with a number of slots which run along the scraper body in a direction parallel to the longitudinal axis of the scraper and which extend in a radial direction into the scraper to a depth sufficient .to allow the tool to flex as it encounters obstructions in a pipeline. At least some of these slots may extend in this radial direction all the way through the walls of the scraper elements. The slots may be filled with a rubberlike substanceto reduce leakage of fluid around the scraper and to lend structural support to the slotted tool.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a cross sectional view of an embodiment of the dumbell scraper of this invention passing through a pipeline.

FIG. 2 is a cutaway view showing the dumbell scraper of FIG. 1 passing through a pipeline bend.

FIG. 3 is a side view of an embodiment of the slotted dumbell scraper of this invention.

FIG. 4 is an end view of the slotted dumbell scraper of FIG. 3.

FIG. 5 is a cross sectional view of a slotted dumbell scraper as shown in FIG. 3 which is provided with an internal spool piece and a check valve.

FIG. 6 is a side view partly in cross section of a dumbell scraper which is provided with a flex ring.

DESCRIPTION OF PREFERRED EMBODIMENT Referring to FIG. 1 we see a cross sectional view of an embodiment of the scraper of this invention. The scraper, which may be made from a wear resistant metal such as steel, generally comprises an elongate dumbell-shaped body 10 having a longitudinal axis 14 at least twice as long as the internal diameter of the pipe to be scraped. The body 10 includes a first scraper member 11 and a second scraper member 12 operatively connected to an elongate connector member 13. These members may be formed in one piece as in the embodiment of FIG. 1 or may comprise separate elements operatively connected by suitable connecting means such as welds or threaded connections.

The scraper members 11 and 12 preferably have curved scraping surfaces which have a substantially circular cross section when the section is taken perpendicular to the longitudinal axis 14 of the scraper body 10 as well as an at least partially curved cross section when the section is taken in a plane parallel to the axis 14 (i.e., the plane of FIG. 1). The surfaces of the scraper members 11 and 12 may conform, at least in part, to the shape of a spherical body or may take the form, in part, of any ellipsoid-like body which will suitably maintain substantial contact between the surface of the scraper members 1 l and 12 and the walls of a pipeline or tubing string 17 as the tool passes around a sharp bend in that pipeline such as is illustrated in FIG. 2. (As used herein, the term ellipsoid-like is meant to include bodies which may in part comprise truncated cones and cylinders joined in such a way that the general shape of the body they form is similar to an ellipsoid even though a cross sectional view would show a perimeter comprising a number of straight line segments.) Portions of the scraper members II and 12 not expected to contact the pipe as the tool passes through bends therein, such as bend 18 (FIG. 2), need not conform to this ellipsoid-like shape. Thus, the leading and trailing ends 15 and 16 of the scraper 10 may be squared off as in the embodiment of FIG. 1.

The connector member 13 of the scraper 10 preferably has a maximum cross sectional thickness when taken in a plane perpendicular to the longitudinal axis 14 of the scraper body 10 substantially less than the maximum thickness of the first and second scraper members 1 1 and 12 when taken in a parallel plane. This cross sectional thickness of the connector member 13 is preferably sufficiently small to allow the scraper 10 to negotiate pipeline bends such as bend 18 (FIG. 2). An appropriate thickness for the connector member I3 may be determined from the radius of curvature 19 of the minimum radius bend 18 the scraper is expected to pass through, the shape and size of the scraper members 1 1 and 12, the length of the connector member 13, and the internal diameter of the pipe 17 through which the tool must pass.

The scraper 10 may be provided with a fluid bypass means such as a conduit or through-bore means 20 to allow some fluid to pass through the scraper body 10 as the scraper 10 moves through the pipe to be scraped. Preferably the throughbore means 20 is operatively associated with a valve means such as check valve 21 which may be operatively connected to the scraper body 10 by connector means such as threaded connection 22. The check valve 21 allows a displacing fluid to partially bypass through the scraper 10 as the scraper 10 moves from right to left with respect to the tubing 17 (in the view of FIG. 1), but if the scraper moves from left to right with respect to the tubing 17, ball 23 will seat in seat means 24 closing the through-bore 20 to fluid flow. The scraper 10 is preferably pumped into a well tubing to be scraped oriented so that fluid may partially bypass through the check valve 21 as the scraper 10 is pumped down the hold, but not as it is pumped back out. This allows parafiin displaced in front of the scraper 10 on the way down the tubing to be diluted ahead of scraper 10 so that it may be more readily pushed ahead of the scraper as it moves down the tubing. Furthermore, it is expected that displacement of the scraped paraffin out of the tubing when fluid movement is reversed to recover the scraper and paraffin will be enhanced by such dilution.

The scraper body 10 may also be provided with fishing neck means, such as ridge 25 which is provided with recessed groove 26 on the inner edge thereof, to facilitate the retrieval of the scraper 10 with wire line fishing tools of aconventional type should the scraper 10 be stuck in the pipe being scraped.

In a preferred embodiment of the invention, the body of a scraper 27 (FIG. 3) shaped as heretofore described may be provided with a number of longitudinal slots 28 and 29 which run along the scraper body in a direction substantially parallel to the longitudinal axis of symmetry 30 of the scraper 27. These slots 28 and 29 are preferably recessed into the surface of the scraper 27 in a radial direction with respect to the substantially circular cross section of the scraper 27 (see FIG. 4). At least some of the slots 28 and 29 preferably extend axially from the ends 33 and 34 of the scraper 27 along the respective scraping surfaces 31 and 32 of the scraper members 35 and 36. The slots 28 and 29 preferably are recessed radially into the scraper members 35 and 36 a distance sufficient to allow the scraper members 35 and 36 to flex when encountering an obstruction in a pipeline, such as a crimp or weld slag, which might cause an inflexible scraper to become stuck in the pipe. In a preferred embodiment at least some of these slots 28 and 29 may extend radially all the way through the walls of a scraper member as slots 28 extend through member 35. To prevent fluid leakage around a slotted scraper 27 as it passes through a fluid filled pipeline the slots 28 and 29 may be filled with a flexible rubberlike material such as neoprene 29a as shown in FIG. 5.

The slotted scraper of FIGS. 3 and 4 may be provided with a means such as spool piece 44 (FIG. 5) which is adapted to be operatively associated with a check valve means 45. The spool piece 44 provides internal support for the scraper 27.

In another embodiment of the invention (FIG. 6), the flexibility of a dumbell scraper 39 may be increased by providing the scraper members 37 and 38 with a circumferential groove running perpendicular to the longitudinal axis of the scraper, such as groove 40, adapted to accept a substantially circular flex means such as flex ring 41 which has a wear resistant surface 42. The ring 42 is preferably shaped to generally conform to the shape of the scraper member 38, but may have a cross sectional thickness when taken in a plane perpendicular to the I longitudinal axis of the scraper 39 greater than the cross sectional thickness in a parallel plane of any part of the scraper member 38. The flex ring 41 is preferably adapted to expand or contract as the scraper 39 passes through a pipeline of varying diameter. A flexible sand seal means 43, such as a band of rubber, may be disposed in the groove 40 beneath the flex ring 41 to prevent sand or other solid matter from becoming lodged beneath the flex ring 41 and thus limiting the ability of the ring 41 to contract.

In summary, this invention provides an apparatus for scraping deposits from the interior of a tubular pipe comprising an elongate scraper body formed from a wear resistant material and having a longitudinal axis of symmetry at least twice as long as the internal diameter of the pipe to be scraped. The scraper body comprises two scraper members, the surfaces of which at least partially conform to the shape of an ellipsoidlike body and which have a substantially circular cross section in a plane perpendicular to the longitudinal axis of the apparatus. The scraper body also comprises a connector member of substantially reduced radial thickness operatively connected to said scraper members whereby said apparatus may negotiate bends in a pipeline. In a preferred embodiment at least one of the scraper members is provided with a number of elongate slots which run parallel tothe longitudinal axis of symmetry of the scraper body and at least some of which slots extend in a radial direction from the axis of symmetry completely through the scraper member to allow the member to flex when encountering an obstruction in the pipeline. At least some of the slots may be filled with a rubberlike material.

In operation, the scraper of this invention may be used according to conventional through the flowline techniques. For example, the scraper may be inserted into a production flowline at a surface location and pumped back through the flowline to a marine well head, through the well head assembly and down the tubing of a well to be scraped. The scraper is preferably pumped to a location in the tubing below a paraffin deposit to be removed. At this point, the direction of fluid flow through the tubing is reversed and the scraper is pumped back out of the well. The tool then passes through the well head assembly and the flowline back to the point of insertion, with the pumped displacing fluid bringing along with it paraffin which has been scraped from the walls of the pipe through which it passes.

I claim as my invention:

1. An apparatus for scraping paraffin deposits from the interior of a tubular pipe comprising:

an elongate scraper body having a longitudinal axis at least twice as long as the internal diameter of the tubular pipe;

said scraper body comprising a first scraper member having a curved scraping surface of substantially circular cross section when taken in a plane perpendicular to the longitudinal axis of said scraper body and of at least partially curved cross section when taken in a plane parallel to said axis;

a second scraper member having a curved scraping surface of substantially circular cross section when taken in a plane perpendicular to the longitudinal axis of said elongate scraper body and of at least partially curved cross section when taken in a plane parallel to said axis; and

an elongate connector member operatively connected to said first scraper member and said scraper member, said elongate connector member having a maximum cross sectional thickness perpendicular to the longitudinal axis of said scraper body less than the maximum diameter of said first and second scraper members when taken in a parallel plane;

said first and second scraper members each being provided with a number of slots which extend along the surface of said scraper members longitudinally in a direction substantially paralleled to the longitudinal axis of said scraper body and which are recessed into said scraper members in a radial direction with respect to the substantially circular cross section of said scraper members a sufficient distance to allow said scraper members to flex when encountering an obstruction in the well tubing.

2. The apparatus of claim 1 including:

through-bore means passing axially through said scraper body whereby a fluid may flow through said through-bore means; and check valve means operatively associated with said throughbore means. 3. The apparatus of claim 1 wherein at least some of said slots are filled with a rubberlike material.

4. An improved apparatus for scraping paraffin deposits from the interior of tubular pipe of the type comprising an elongate scraper body having a longitudinal axis at least twice as long as the internal diameter of the tubular pipe; said scraper body comprising first and second scraper members having a curved scraping surface of substantially circular cross section when taken in a plane perpendicular to the longitudinal axis of said scraper body and of at least partially curved cross section when taken in a plane parallel to said axis; and an elongate connector member operatively connected to said first scraper member and said second scraper member, said elongate connector member having a maximum cross sectional thickness perpendicular to the longitudinal axis of said scraper body less than the maximum diameter of said first and second scraper members when taken in a parallel plane, the improvement comprising: provided in at least one of said first and second scraper members, a circumferential groove adapted to accept a substantially circular flex ring;

at least one substantially circular flex ring operatively positioned in said groove whereby said flex ring may expand or contract as said apparatus passes through a pipeline of varying internal diameter to scrape the internal walls of said pipeline;

and a flexible sand seal means disposed in said groove beneath said flex ring to prevent matter from being deposited beneath said flex ring.

5. The apparatus of claim 5 wherein at least some of said slots are filled with a rubberlike material.

6. An apparatus for scraping deposits from the interior of a tubular pipe comprising an elongate scraper body formed from a wear resistant material and having a longitudinal axis of symmetry at least twice as long as the internal diameter of the pipe to be scraped;

said scraper body comprising two scraper members the surfaces of which at least partially conform to the shape of an ellipsoid-like body and which have a substantially circular cross section in a plane perpendicular to the longitudinal axis of the apparatus;

said scraper body also comprising a connector member of substantially reduced radial thickness operatively connected to said scraper members whereby said apparatus may negotiate bends in said pipe;

at least one of said scraper members being provided with a number of elongate slots which run parallel to the longitudinal axis of symmetry of the scraper body and at least some of which slots extend in a radial direction from said axis of symmetry completely through said scraper member to allow said scraper member to flex when encountering an obstruction in said pipe. 

1. An apparatus for scraping paraffin deposits from the interior of a tubular pipe comprising: an elongate scraper body having a longitudinal axis at least twice as long as the internal diameter of the tubular pipe; said scraper body comprising a first scraper member having a curved scraping surface of substantially circular cross section when taken in a plane perpendicular to the longitudinal axis of said scraper body and of at least partially curved cross section when taken in a plane parallel to said axis; a second scraper member having a curved scraping surfaCe of substantially circular cross section when taken in a plane perpendicular to the longitudinal axis of said elongate scraper body and of at least partially curved cross section when taken in a plane parallel to said axis; and an elongate connector member operatively connected to said first scraper member and said scraper member, said elongate connector member having a maximum cross sectional thickness perpendicular to the longitudinal axis of said scraper body less than the maximum diameter of said first and second scraper members when taken in a parallel plane; said first and second scraper members each being provided with a number of slots which extend along the surface of said scraper members longitudinally in a direction substantially paralleled to the longitudinal axis of said scraper body and which are recessed into said scraper members in a radial direction with respect to the substantially circular cross section of said scraper members a sufficient distance to allow said scraper members to flex when encountering an obstruction in the well tubing.
 2. The apparatus of claim 1 including: through-bore means passing axially through said scraper body whereby a fluid may flow through said through-bore means; and check valve means operatively associated with said through-bore means.
 3. The apparatus of claim 1 wherein at least some of said slots are filled with a rubberlike material.
 4. An improved apparatus for scraping paraffin deposits from the interior of tubular pipe of the type comprising an elongate scraper body having a longitudinal axis at least twice as long as the internal diameter of the tubular pipe; said scraper body comprising first and second scraper members having a curved scraping surface of substantially circular cross section when taken in a plane perpendicular to the longitudinal axis of said scraper body and of at least partially curved cross section when taken in a plane parallel to said axis; and an elongate connector member operatively connected to said first scraper member and said second scraper member, said elongate connector member having a maximum cross sectional thickness perpendicular to the longitudinal axis of said scraper body less than the maximum diameter of said first and second scraper members when taken in a parallel plane, the improvement comprising: provided in at least one of said first and second scraper members, a circumferential groove adapted to accept a substantially circular flex ring; at least one substantially circular flex ring operatively positioned in said groove whereby said flex ring may expand or contract as said apparatus passes through a pipeline of varying internal diameter to scrape the internal walls of said pipeline; and a flexible sand seal means disposed in said groove beneath said flex ring to prevent matter from being deposited beneath said flex ring.
 5. The apparatus of claim 5 wherein at least some of said slots are filled with a rubberlike material.
 6. An apparatus for scraping deposits from the interior of a tubular pipe comprising an elongate scraper body formed from a wear resistant material and having a longitudinal axis of symmetry at least twice as long as the internal diameter of the pipe to be scraped; said scraper body comprising two scraper members the surfaces of which at least partially conform to the shape of an ellipsoid-like body and which have a substantially circular cross section in a plane perpendicular to the longitudinal axis of the apparatus; said scraper body also comprising a connector member of substantially reduced radial thickness operatively connected to said scraper members whereby said apparatus may negotiate bends in said pipe; at least one of said scraper members being provided with a number of elongate slots which run parallel to the longitudinal axis of symmetry of the scraper body and at least some of which slots extend in a radial direction from said axis of symmetry completely through said scraper member to Allow said scraper member to flex when encountering an obstruction in said pipe. 